Bispectral and trispectral (ultraviolet through visible and far infrared electromagnetic radiation) screening smokes are of increased interest to militaries due to the proliferation of ultraviolet sensors, thermal imaging, night vision, and other thermal guided threats. Multispectral screening smoke increases the warfighter's level of protection against emerging threats and methods of detection, while combining technologies to reduce logistical load. However, there is no known high efficiency bispectral obscurant smoke or continuously burning grenade. Ideally, the soldier would have a pyrotechnic device producing an obscurant that can provide a high performance bispectral and/or trispectral obscuration with continuous cloud production. Continuous cloud production is desirable to reduce transmittance and it is desirable to obtain obscurants that preferably block or reduce transmittance in the wavelengths between 40 nm to 100 μm (ultraviolet through visible to infrared).
Metal Organic Frameworks (“MOFs”) are compounds that have metal ions coordinated to organic ligands. These coordination networks results in a stable porous structure usable for the storage of small molecules. MOFs possess appealing characteristics that have made them successful in applications such as gas purification and separation, catalysis, and sensors. However, to date no work has been done to explore the use of MOFs and MOF composites in obscurant chemistry. The structural components of MOFs are uniquely suited to smoke production. In particular, MOFs consist of a self-contained pyrotechnic mix, including a fuel (metal node) and oxidizer (ligand). MOFs and MOF/composites can replace, supplement, or enhance components of pyrotechnic smoke formulations in order to produce an ultraviolet through infrared blocking smoke.
MOFs are known for use as pyrotechnic materials. Blair et al. teaches MOFs including Ca, Sr, Ba, K, and Cs metal as fuels, and organic linkers as oxidizer, in “Metal-organic fireworks: MOFs as integrated structural scaffolds for pyrotechnic materials,” Chem. Commun., 2015, 51, 12185. However, Blair, et. al. does not discuss or concern generating smoke that can obscure in the ultraviolet, visible, and infrared regions of the electromagnetic spectrum.